The Compact Disc Erasable (CD-E) disc has been developed with Ag-In-Sb-Te phase-change recording material. The disc has been designed for recording at a speed twice that of conventional CD's. The CD-E disc has high modulation, high sensitivity, wide power margin after 1000 overwrite cycles and high reliability. It is readable using CD-ROM players and recordable using CD-R recorders with minimum modification.
Following unification of DVD-ROM format, standardization of DVD-RAM specification is now under way. Phase change disks will be employed for DVD-RAM since ROM drives will hardly be implemented with polarization optics. It is said that a couple of proposals in connection with recording method are being discussed in the standardization group. These are Land/Groove recording and groove recording. We have conducted write and read experiment employing the groove recording method for our phase change discs. We report in this article signal properties of our phase change discs based on the groove recording method.
Introduction of ISO 4th ganaration 5.25"magneto-optical Disk. Major Disk parameters as of August 1996 in ISO discussion. And Sony's design concept to achieve 8X density. (PRML with adaptive amplitude reference level, Phase error detection method using ML result)
A dual focus optical head with a holographic optical element (HOE) that can read both 0.6 mm disks and 1.2 mm disks has been developed. We evaluated allowable ranges for the misalignment of the HOE, the wavelength deviation, the disk tilt angle and the defocus distance. It was found that except for the issue of coma aberration, the allowable ranges are wide enough for mass-production. When an objective lens having initial coma aberration is used with a plane-type HOE, coma aberration still remains for the 1.2 mm disk after performing skew adjustment for the 0.6 mm disk. We found that the aberration can be reduced by integrating an HOE with the objective lens on its first surface.
We have developed a new hard disk interface device suitable for transferring digital video signals, which complies with SCSI-2 (Fast Wide SCSI). This device can guarantee continuous transfer of video signals with a high bit rate, sending them at 123 Mbps/ch-more than twice as fast as a conventional device. Using this interface, we have developed an experimental video hard disk system capable of realtime recording and playing back of non-compressed video signals (conventional TV).
Digital picture recording was generalized by standardization of JPEG technology. Now it is usable on ordinary PCs, and contribute greatly to the world of multimedia technology. This time we have developed a video disk recorder which uses the M-JPEG format and has a standard 1 gigabyte media storage capacity. This video disk recorder has a field recording capability of 20 minutes with audio. And in case of the still picture, it's capable for recording 36000 frames. This report describes the outline of the video disk recorder, characteristics of the recording format and its applications.